This invention is in the field of medical materials and devices.
It is known to react polyvinylpyrrolidone (N-vinyl-2-pyrrolidone) with an isocyanate prepolymer and cure the reaction product to form polyvinylpyrrolidone bonded to a polyurethane to form, for example, coatings having a very low coefficient of friction when wetted with an aqueous solution. Reference may be had to U.S. Pat. Nos. 4,100,309 and 4,119,094 which are incorporated herein by reference. Such material does not dissolve when exposed to water or body fluids. It is also known to form complexes of iodine with polyvinylpyrrolidone (see U.S. Pat. Nos. 2,739,992 and 2,706,701). This material is water-soluble and would be washed away by body fluids.
In U.S. Pat. No. 3,235,446 to Shelanski a polyurethane foam or film is disclosed which is complexed with iodine for release thereof in water. There is no indication in the Shelanski '446 disclosure to provide a polyurethane-polyvinylpyrrolidone interpolymer and the Shelanski product suffers a drawback of releasing elemental iodine which is undesirable because of its irritating effect on the skin. U.S. Pat. No. 3,216,579 to Shelanski, et al. discloses a water-insoluble form of polyvinylpyrrolidone adsorbed on a granular synthetic calcium silicate. There is no suggestion by Shelanski, et al. to form a polyurethane-polyvinylpyrrolidone interpolymer for use as a medical material, e.g., film or foam.
German Offlegungsschrift No. 25 57 607 to Blank, et al. discloses a polymer containing 20-100 wt. % vinylpyrrolidone and 0-80 wt. % of other monomer units, which can be hydrophilic monomer units such as acrylic acid, methacrylic acid, itaconic acid and/or hydroxyethyl methacrylate, or hydrophobic monomer units such as alkyl acrylate and/or methacrylate. Adducts of iodine can be formed by contacting the polymer with iodine in the liquid phase at room temperature. There is no indication by Blank, et al. to use a polyvinylpyrrolidone polymer in combination with a second polymer such as a polyurethane combined or complexed as an interpolymer.
In accordance with this invention an anti-bacterial agent which for some applications is also an anti-fungal agent such as iodine is complexed with polyvinylpyrrolidone (PVP), which PVP has been rendered insoluble in water and body fluids by being complexed with a polyurethane, thus rendering the polyvinylpyrrolidone insoluble while still permitting the release of the anti-bacterial agent. The thus-formed material is useful per se to supply an anti-bacterial agent in the form of a pad (such as a foam pad), a bandage or the like or as a coating for a medical device such as a catheter. The material may be used as a foam, for example, between the toes in the treatment of athlete's foot (tinia pedis) which involves a fungal infection by trychophyton mentagrophytes.
Previously, iodine complexed with insoluble polyvinylpyrrolidone has been made by using special alkaline catalysts when polymerizing (see U.S. Pat. No. 3,136,755 to Grosser, et al. incorporated herein by reference) but these complexes are not useful for coating medical devices because the polymeric-iodine complexes are not soluble in any solvents. Furthermore, the Grosser, et al. polyvinylpyrrolidoneiodine complexes cannot be used as a coating since these complexes are insoluble, and the Grosser, et al. complexes do not form the useful sponge-like materials of this invention.